Search form

Nutrition - the essentials

What nutrients do we need for ongoing health?

According to the World Health Organization's September 2014 dietary guidelines (WHO), “various nutrients, including water, are essential for growth, reproduction and good health”; they include macronutrients (proteins, simple and complex carbohydrates, fats and fatty acids), needed in relatively large quantities, and micronutrients (vitamins, minerals, trace elements and phytochemicals), required in relatively smaller quantities but also crucial for various physiological processes.

What constitutes a healthy diet?

To function optimally and avoid major disease, humans need a balanced, varied diet containing enough nutrient-rich foods to provide the body with the key macro- and micronutrients it needs. It breaks these foods down to extract carbohydrates, protein, fats and oils, vitamins, minerals, trace elements, phytochemicals, fibre and resistant starch.

In a healthy diet, all these elements are present in sufficient (but not excessive) amounts to enable the body to function optimally, fight off infections and prevent the development of numerous health problems including several chronic preventable diseases.

What constitutes a healthy diet will vary depending on an individual’s age, gender, lifestyle, and level of physical activity, but most nutritional experts agree that it should include an optimal amount and variety of whole, nutrient-rich foods on a daily basis, sufficient water and minimal amounts of unhealthy fats, sugars, salt and alcoholic beverages.

To reduce their risk of developing chronic diseases and ensure an adequate intake of key nutrients and dietary fibre, WHO recommends that adults eat at least 400 grams – five portions – of fruit and vegetables a day, preferably varied, fresh and in season, and not including potatoes, sweet potatoes, cassava and other starchy roots.

To avoid unhealthy weight gain, less than 30 percent of total kilojoules should be coming from fats, cautions WHO. At least two thirds of these should be unsaturated fats (such as those in fish, avocado, nuts and sunflower, canola and olive oils), with no more than 10 percent saturated fats (those in fatty meat, palm and coconut oil, cream, cheese, butter, ghee and lard), and less than one percent industrial trans fats (those typically included in fried, processed, fast and snack food, frozen pizzas, pies, biscuits, margarines and spreads).

WHO also advises limiting the intake of free sugars (naturally occurring and in processed foods) –to less than 10 percent of total energy, for dental health and to curb weight gain. That’s equivalent to 50 grams or around 12 level teaspoons a day; half that for additional health benefits.

To help prevent hypertension (high blood pressure) and reduce the risk of heart disease and stroke, WHO recommends consuming a maximum of five grams of iodised salt (around one teaspoon) per day – far less than average consumption worldwide (9–12 grams per day).

It also advises that adults get at least 3.5 grams daily of potassium (most easily done by eating more fruits and vegetables), as potassium can mitigate the negative effects of high sodium (salt) consumption on blood pressure, lowering CVD risks.

Dietary recommendations made by governments and public health bodies around Australia are in line with (or more prescriptive than) WHO’s dietary guidelines.

Are Australians following experts’ dietary guidelines?

With all the clean, high-quality food our nation’s farmers produce, you’d think Australians would be among the healthiest citizens on Earth.

That’s not the case, however: most Australians’ consumption of whole, fresh, minimally processed foods such as wholegrains, legumes, fruits and vegetables is significantly lower than public health experts recommend.

At the same time, our average intake of unhealthy fats, sugar and salt has risen dramatically in recent decades, largely as a result of eating more processed and takeaway foods that are high in kilojoules (as well as unhealthy fats, salt, sugar and other additives). As a consequence we’re consuming far more energy than we’re expending.

Indeed, Cancer Council Australia CEO Professor Ian Olver warned in 2011 that, if Australian adolescents’ poor diet and exercise habits continue, “We may see today’s teenagers dying at a younger age than their parents’ generation for the first time in history.”

Successfully encouraging people to adopt balanced, nutrient-rich diets high in dietary fibre and lower in kilojoules, ‘bad’ fats, sugar and salt, is crucial if we’re to halt our nation’s obesity epidemic and reduce the incidence of chronic diseases.

Governments, community organisations, consumer groups and the agricultural, food processing and retail industries all have roles to play in encouraging people to eat less ‘fast’ and snack food and more fresh, minimally processed and sustainably produced food – and in supporting those trying to meet those needs.

“Diet can depend on an individual’s food choices, but also the availability and affordability of healthy foods, and sociocultural factors,” states WHO’s latest dietary factsheet. “Therefore, promoting a healthy food environment requires involvement across multiple sectors and stakeholders, including government, public and private sectors.”

Diet and disease

A growing body of research links healthy food and beverage choices with reduced risk of developing several chronic preventable diseases. According to WHO's latest dietary factsheet (September 2014), “A healthy diet helps protect against malnutrition in all its forms, as well as non-communicable diseases (NCDs), including obesity, diabetes, heart disease, stroke and cancer.”

Numerous epidemiological studies, summarised in the Australian Dietary Guidelines, by WHO and elsewhere point to the health benefits of eating a wide variety of nutritious foods, especially vegetables, fruit, legumes and wholegrains.

Fruit and vegetables

The federal government’s ‘Go for 2+5’ public health campaign goes beyond WHO’s recommendations for fruit and vegetable consumption, advising that for optimal health, adults eat at least two (150g) serves of fruit and five (75g) sees of vegetables a day – and that teenagers, adult males and pregnant woman add up to 2.5 more serves to their daily minimum.

The government based its recommendations on a growing body of scientific research, examined by the National Health and Medical Research Council (NHMRC) and others, that links higher daily consumption of a variety of fruit and, particularly, of different coloured vegetables, with reduced risk of several major preventable illnesses including cancers of the mouth, oesophagus, stomach, colon and bowel; type 2 diabetes; and cardiovascular disease (CVD).

Eating more fruit and vegetables may also reduce a person’s risk of developing mental health problems, too: a recent, large-scale British health survey found that those eating five serves daily of fruit and veg a day were significantly less likely to develop mental illnesses than those eating only one or two serves.

Wholegrains

All wholegrains – oats, barley, whole wheat, brown rice, quinoa – are rich in beneficial compounds: the outer layer or bran is high in fibre, omega-3 fatty acids, vitamins and minerals; the main section or endosperm is principally starch; and the heart or ‘germ’ is a potent source of vitamin E, folate, thiamine, phosphorus and magnesium. Wholegrains are also cholesterol-free, low in saturated fats and an important source of carbohydrates.

According to the USDA, a diet high in wholegrains has numerous health and nutritional benefits. Numerous epidemiologic studies have found that regular consumption of wholegrains is associated with reduced incidence of several major diseases, including hypertension, stroke, CVD, type 2 diabetes, some cancers and various inflammatory conditions.

As noted in the Australian Consumer Association’s CHOICE Magazine (April 2013), “There’s evidence that dietary patterns consistent with relatively high amounts of wholegrains, in conjunction with a balanced diet, may be associated with excellent nutritional levels, quality of life and survival in older adults. There is also a positive association between consumption of wholegrain cereals and decreased risk of heart disease and excessive weight gain.”

Regular consumption of oats may be particularly beneficial, notes CHOICE, as they are high in beta-glucan, a soluble fibre that helps reduce bad cholesterol levels; have a low glycaemic index (GI), which helps prevent the onset of type 2 diabetes; and are high in essential minerals and B vitamins.

Dietary fibre

Several studies have found an association between higher consumption of dietary fibre (particularly resistant starch) and reduced incidence of an array of problems of the gut and bowel, from constipation to irritable bowel syndrome (IBS) to colorectal cancer, and to the development CDV. To protect against these, the Victorian Government Department of Health advises that adults eat 25-30 grams of soluble and insoluble fibre a day, including resistant starch.

High consumption of trans fatty acids, saturated and polyunsaturated fats is strongly implicated in the development of several cancers and CVD.

High salt consumption is associated with high blood pressure and CVD.

High fat and sugar consumption is linked to overweight and obesity, and thus to obesity-related health problems.

High levels of ‘bad’ (low-density) cholesterol and low levels of ‘good’ (high-density) cholesterol are linked with the development of heart disease and stroke.

A high glycaemic index (GI), such as may result from eating a diet high in refined carbohydrates, is linked with the development of type 2 diabetes.

A low intake of dietary fibre, typically associated with low consumption of whole, fresh and minimally processed foods, is associated with various problems of the gut and bowel including irritable bowel syndrome (IBS) and colorectal cancer.

Inadequate intake of calcium and vitamin D, through insufficient exposure to sunlight and a diet too low in leafy greens and dairy produce, is associated with higher incidence of osteoporosis and bone fracture.